I was reading Jacob's old book on ignitions and noted that he stressed that one ought to use a variable saturation coil; I gather that the idea is similar to a magamp in that the core partially saturates, decreasing the inductance for a smaller LR charge up time and hence more net stored energy at higher RPM. It seems that his variable saturation canister coils have been out of production for years and I can find no good specs on them.

In practice, does that feature make a notable improvement over a standard coil?

A fine work of advertising fiction, if you're into that sort of thing. There was a relatively minor amount of decent science in it; the rest is gussied-up advertising for Jacobs' unreliable, overpriced garbage.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Their lifetime warranty meant nothing as well.

I see them as selling hoax boxs and BS. The connectors on "the best plug wires in the world" that they sell are a joke.

There are plenty of good ignition options out there, but they are not one of them.